In nature, fungi produce a number of biochemical and morphological responses to other microorganisms as a means of competing for resources. These interactions typically fall into two categories: antagonism from a distance (in which antagonistic bioactive compounds are leached into the environment to inhibit the growth of surrounding organisms), and physical antagonism (in which the fungus comes into physical antagonistic contact with a competing microorganism).
Fungi also have a dynamic range of responses to the antagonism of competing microorganisms, including rapid recovery, fruiting and sporulation, and the creation of physical barriers between the mycelial mass and the competing organism (such as thickened zones of mycelium at the interface, extra-cellular pigmentation/melanin).
As is known, U.S. patent application Ser. No. 12/001,556, filed Dec. 12, 2007, now U.S. Pat. No. 9,485,917, issued Nov. 8, 2016, describes various techniques for making a biomaterial composed of a substrate of discrete particles and a network of interconnected mycelia cells extending through and around the discrete particles and bonding discrete particles together. This biomaterial leverages the tenacious strength of fungal vegetative mycelium.
It is an object of the invention to obtain specific tissue morphologies in the fungus used for making composite materials by placing the binding organism in competitive contact with a modulating organism.
It is another object of the invention to selectively inhibit the growth of a binding organism used in making a biomaterial via application of a modulating organism to the binding organism.
Briefly, the invention provides a method for stimulating the expression of specific tissue morphologies in filamentous fungi via interactions with competing microorganisms. These tissue morphologies are described within the context of biomaterial production utilizing the vegetative mycelium of filamentous fungi, and the morphologies produced via the described competitive interactions may provide unique material physical properties within the said context. Relationships and interactions are described between A) a binding organism (the filamentous fungus being cultivated as a biomaterial), and B) a modulating organism (a microorganism introduced to the binding organism in order to elicit the expression of tissue morphology specific to the competitive interaction of the binding organism with the modulating organism and/or to completely inhibit the growth of the binding organism as a means of selectively controlling the boundaries of growth of the binding organism.
The process stimulates multiple tissue morphologies, with each providing particular functionalities within a given mycelium-based biomaterial based on the organisms selected and the method of modulating organism dispersal in relation to the binding organism. The specific interactions, and the results of those specific interactions, are additionally controlled by the selection of organisms based on A) application, B) environmental context, C) nutritive context, and D) ecological context.
In particular, the invention provides a method of making a composite biomaterial comprising the steps of selecting a binding organism based on the material physical properties required for the composite biomaterial and selecting a modulating organism based on a desired effect of the modulating organism on the binding organism.
The method requires the steps of inoculating a mass of discrete substrate particles with the binding organism; applying the modulating organism to the combination of binding organism and discrete substrate particles; and incubating the combination of binding organism, discrete substrate particles and modulating organism in an environment that is conducive to the growth of both the binding organism and modulating organism to produce a composite biomaterial having the discrete substrate particles bound together by the binding organism and the modulating organism imparting said desired effect on the binding organism.
Referring to FIG. 1, by placing a binding organism 10 on a modulating organism 11 in binary opposition to one another a clear boundary of interaction is created at the interface. This can function as a method of describing specific growth boundaries for the binding organism; the binding organism can be restricted to growing and expanding within defined parameters within a given volume or two-dimensional plane.
Referring to FIG. 2, wherein like reference characters indicate like parts as above, a binding organism 10 growing on a plate 12 without a modulating organism provides a smooth-looking appearance at a top surface.
Referring to FIG. 3, wherein like reference characters indicate like parts as above, the binding organism 10 is grown with the modulating organism 11 homogeneously disbursed throughout the growth medium. In this case, the binding organism 10 is the only growth visually apparent, but the overall density of growth has been reduced due to the interaction of the modulating organism 11.
The “growth medium” is the nutrient substrate that the binding and modulating organisms are growing on. This is most often discrete lignocellulose particles.]
By homogeneously disbursing the modulating organism 11 throughout the volume of the growing binding organism 10, the overall density of the binding organism's mycelial colonization can be reduced via the competitive action of the modulating organism 11.
This method can be used for producing mycelium-based materials that require a reduced density of mycelial colonization without the need for chemical, nutritive, or environmental retardation of colonization.
Referring to FIG. 4, wherein like reference characters indicate like parts as above, by controlling the capacity of the modulating organism 11 to utilize the nutrition and environmental context, while also controlling the selection of binding organism 10 and modulating organism 11, a relationship can be developed that results in the binding organism 10 expressing a denser quality of mycelial colonization when in contact with the modulating organism 11 than would be typical. This can be utilized for increasing the density of growth for a given mycelium-based biomaterial, thereby modulating the material's flexural strength, compressive strength, thermal characteristics or stiffness.
As illustrated, the binding organism 10 has expanded over top of the modulating organism 11 (located at 4 points along the outside of the culture plate 12), leading to denser mycelial colonization of the binding organism 10 when coming into contact with the modulating organism 11.
When placed in binary opposition either the binding organism 10, the modulating organism 11, or both organisms can produce extra-cellular pigments 13 (such as melanin) at the interface between the two organisms. Based on species selection, this interaction can produce specific aesthetic results, which can be used to pigment the surface (or selected areas of the surface) of a given mycelium-based biomaterial.
A pigmentation response during binary interaction of a binding organism 10 with a modulating organism 11 resulted in a very dense production and depositing of melanin 13 at an interface between the two organisms.
Referring to FIG. 5, wherein like reference characters indicate like parts as above, by either placing the binding organism 10 and modulating organism 11 in a binary interaction, or by otherwise disbursing the modulating organism 11 throughout the mass of the binding organism 10, the induction of primordia/sporocarps can occur. Depending on the maturity and location of sporocarps on the given mycelium-based biomaterial, the strength and/or cushioning characteristics of the material can be increased.
As illustrated, in response to the modulating organism 11, the binding organism 10 (the only growth visually apparent) expanded and covered a selectively placed modulating organism 11, at which point, the binding organism 10 developed a large primordium 14 in the exact footprint of the modulating organism 12.
Based on organism selection, and placement of the binding organism 10 with the modulating organism 11, a thickened and/or aerial quality of vegetative growth can be induced at the interface between the binding organism 10 and the modulating organism 11. In this case, the thickened mycelium can impart additional cushioning or strength characteristics to the given mycelium-based biomaterial.
By homogeneously disbursing the modulating organism 11 throughout the binding organism 10, or selectively disbursing the modulating organism 11, and depending on organism selection, a generalized aerial quality of vegetative growth can be achieved. This aerial growth can provide additional cushioning and aesthetic characteristics to a given mycelium-based biomaterial.
A “fuzzy” aerial mycelium expressed across the surface of a mycelium-based biomaterial via the homogeneous disbursing of a modulating organism 11 throughout the volume of the binding organism 10.
The method for stimulating the expression of specific tissue morphologies in filamentous fungi comprises the following process steps:                1. Select a binding organism based on the desired material performance, as well as nutritive and environmental context for cultivation.                    Examples of a binding organism would be filamentous fungi that produce mycelium that has attractive material physical properties based on the intended application (for example, high tensile strength for application as a low-density packaging material). Particularly, a filamentous fungi from the Basidiomycetes, such as Ganoderma tsugae, Trametes hirsuta, or Ganoderma oregonense.                         2. Select a modulating organism based on the desired effect on the binding organism, desired method of disbursal, and nutritive and environmental context for cultivation. The modulating organisms ecological niche in relation to the binding organism's ecological niche should be considered, as well as the modulating organisms ability to utilize the nutritive and environmental context.                    Examples of a modulating organism would be fungi or bacteria that specifically demonstrate a competitive/antagonistic dynamic with the binding organism. Examples include, but are not limited to:                            Bacteria: Pseudomonas sp., and Bacillus sp.                Fungi: Zygomycetes, such as Rhizopus sp. and Mucor sp., Ascomycetes, such as Aureobasidium sp., Trichoderma sp., Penecillium sp., Chrysonillla sp., and Aspergillus sp. Basidiomycetes, such as Phanerochaete sp., Trichaptum sp., Stereum sp., Phlebia sp., Laetiporus sp., and Peniophora sp. Yeast, such as Saccharomyces sp.                                                3. Inoculate the target media for colonization/supporting mycelia colonization with the binding organism. This is the discrete particles to be bound together into a composite material by the mycelium of the binding organism, most often discrete lignocellulose particles (such as agricultural by-products or wood particles).        4. Disburse the modulating organism in relation to the binding organism by:                    a.) Placing the two organisms in a binary interaction, creating a single interface.            b.) Homogeneously disbursing the modulating organism throughout the mass of the binding organism.            c.) Selectively placing the modulating organism through, on, or in opposition to a portion of the overall mass of the binding organism via 4a or 4b.                        5. Incubate the combination of binding and modulating organism within the desired environmental conditions until the desired quality of mycelial growth and tissue morpohology has been achieved.                    This step is highly specific to the intended application. For instance, if the intention is to induce primordia along the interface between the modulating and binding organism to provide a cushioning characteristic, and primordia 2 cm tall are required to achieve the desired cushioning characteristic, incubation would continue until the primordia reach a height of 2 cm.                        6. Further process the biomaterial as necessary                    This is the composite material made up of the discrete lignocellulose particles bound together by the mycelium of the binding organism (which has had a particular expression induced by the modulating organism, and/or had its growth boundaries defined by inhibition of the modulating organism).                        